dolbeab



Patented 28, 1923.

entree stares CLINTON E. DOLBEAB, OF SAN FRANCISCO, CALIFORNIA.

ASSIGNOR T0 INDUSTRIAL RESEARCH 00., OF SAN FRANCISCO. CALIFORNL'R. A BUSTNESS ASSOCIATION.

RECOVEBING ALKALI-I/IE'IMKL SALTS FROIVI BRINES.

No Drawing.

To oZZ whom it may concern:

Be known that l, Cmrrroz: Pl. Donenm, citizen ol the Jnitcd tit residing at the city and county of San Francisco and State of Cali" aria. have invented c'atain new and useful Improvements in Recoverin irikali-Metal Salts :trom Brines. of which the following is a specification.

My invention relates to the treatment oi brincs carry hm alkali metal salts, particu larly a mixture of potassium sodium salts. Its object is to recover said salts by a simple and effective method of precipitation, and to this end my invention consists in the novel method which I shall now lull: describe.

The principle involved in my method is based upon the fact that certain salts ot potassium and sodium are almost insoluble in ammonical solution. I have found that if ammonia is rapidly dissolved in such brine as occurs at Searles Borax Lake or Deep Springs Valley in California. sodium sulfate chielly is first precipitated. firs the solution becomes stronger with annooni-i sodium carbonate and borax. together with practically all the remaining sodium sul- 'late are precipitated. leaving potassium and sodiun'i. chloride alone in solution.

It, now, sodium sulfate in solution is added to the last brine. that is. the strong;- aminoniaeal brine containing the potassium and sodium chlorides. the potassium chloride reacts with the added sodium sulfate. forming potassium sulfate \vhich immediately precipitates from the brine.

In, practice. I lind that the sodium car bouate. sulfate and borate are very complcle ly precipitated during the addition of the auuuonia in the first step of the method as above described. and that the potassium in the form of sulfate is quite cmnplelcly prccipitated by the addition ol sodium sulfate in the second step.

in carrying out the i'net-hod, it is advantageous to initially recover a portion ol the contained sodium sullatc from the raw brine. prior to adding the ammonia. by low ering; the tenujierature of the brine. thus causing: the sodium sulfate to, in part, crystallize out as a hydrated sodium sul fate. This has a three fold economic value. in that, first, the sodium sulfate required for the formation and precipitation 01 the potassium sulfate in the second step of the Application filed January 22. 1923.

Serial No. 614,291.

method is thus obtained: second. the salts remaining: in the briuc are in greater concentration; and. third. a large part ol the comparatively less valuable sodium sul'l'ate is eliminated from the salts recovered.

In practising my method, therefore, .l. first chill the raw brine to near the treesing point ol water. This causes hydrous sodium sulfate to crystallize from too brine. ll then separate this sodium sulfate l'rom the brine for use in the second step of the method. Then I rapidy pass ammonia gas into the brine until the brine has :bsorbed approximately 32); of its weight 0t ammonia. This tends to heat the brine considerably, but the temperature is kept down by appropriate means. and as a result there is precipitation of sodium carbonate, sulfate and borate.

From this point on. the procedure depends upon WllQi'llOl or not it is desired to produce a salt containing all the recovered salts, or one salt containing sodium carbonate. sodium sullate and box-ax. and a se-ond salt containing nearly pure potassium sullatc.

it the lirst mentioned object, namely the recovery (ii a salt containing all the salts. be the result desired. the method is continued as follows: --.-.'l'ter dissolving in water the sodium sull'ate initially recovered by chillin o the brine. this solution is added to the amiuoniacal brine. Potassium sull'ate is l'ormcd and immediately prmtipilates. Then brine and subsequently refined to separate I them from each other.

ll the second n'icntioncd object. uanicly the rccovcryas one product comprising:' a mixture of sodium carbonate. sull'ate and borax. and another product consistin; ol polar iuiu sull'alc. be the result desired. l. separate from the supernatant liquorlhc l'i-rst precipitated salts. to Wit. the sodium carbonate. sull'atc and borax. before :zddiu; to lhc brine the sodium sull'ate solution for the second step. Then (his solution is added to the brine, with the result that a precipitate rich in iiotassium sulfate is formed and linally the mixture of lhe lirst precipitated salts is suitably separated into its component parts. The ammoniacal brine is then subjected to distillation to recover the ammonia for further use.

Concerning the feature of my method which involves the relatively rapid chargmg 01 the brine with ammonia in the lust step, it should be noted as follows. lVere the ammonia slowly d ssolved, an increasingly larger proportion oi the potassium salt would be n-ecipitated with the sodium salts. he potassium precipitates as a sulfate as above explained. In these brines sodium sulfate is always present in cousiderable quantity. it is evident that the potassium chloride, the form in which it is present in the brine, reacts with the sodium sulfate. forming potassium sulfate and. sodium chloride. But this reaction is slow; wherefore, if the ammonia is added rapidly the sodium sulfate, which is decreasii'igly soluble in increasingly strong ammonia solution, is precipitated before any appreciable amount of it has reacted with the potassium chloride. Consequently, the potassium is retained in solution as the chloride, which is decidedly soluble in ammoniacal solution.

In practice, therefore, I find that the more quickly the brine is charged to a high PQICBIltfLg-E with ammonia, the less potassium is deposited. l find that it the brine is charged with ammonia in half an. hour or less, the salts precipitated contain only very small amount of potassium, While it the time taken to charge the brine with ammonia is two hours or more, especially if agitated d urine charging, a large amount of the 1 ol':1ssium present deposited.

In other words the ammonia cl'iarging should be carried out as quiclzlv as mechanically convmiient in order to retain the great-- est quantity oi potassium in solution.

Concerning the use o'l sodium sulfatein the second step of my method, I wish it to he ruulersl'ood that other chemical equivalents may he used. I have mentioned sodium sulfate since it is the most convenient sulfate to be used in conjunction with these -l'urines. as it an be obtained from the brine includes as its chemical equivalent other soluble sulfates.

l. claim I 1. The method oi? recoverinn,- salts from brine containing a mixture oi sodium and mitassium salts. which comprises adding; to

or sodium sulfate.

2. The method of recovcrim salts from brine contain {i a. mixture o't sodium and potiuisium salts, which comprises first, add ingto the brine an'imonia to precipitate the sodium salts and then adding to the am moniacal brine an aqueous solution oi sodium sulfate to recipitate a potassium salt.

3. (lire method of recorerinnsalts from brine containing a mixture of sodium carbonate. sulfate, and borato. and potassiun'i chloride, com prising the precipitation of the sodium carboimte. sulfate and horute by the addition to the brine of ammonia, and the precipitation of the potassium as potassium sulfate by the addition to the ammoniacal brine 01 an aqueous solution of sodium sulfate.

The method of recovering salts from lninecontaining; a mixture of sodium earbonate. sulfate. and borate, and potassium chloride, comprising, first, precipitating the sodium carbonate, sulfate and borate by the addition to the brine oi? ammonia, and then adding to the ammoniacal brine an aqueous solution. of sodium sulfate to form in the brine and 'n'ecipitate therefrom imtassium sulfate.

3. The method of recovering: salts from brine crmtaininif a mixture of sodium and potassium salts connn'isin r initially separating" trom the raw brine, by cooling, a portion oi the contained sodium sulfate; then addin; to the brine ammonia to precipitate the sodium salts; and then adding to the ammoniacal brine an aqueous solution of the sodium sulfate initially separated from the raw brine, to n'ccipitate a potassium salt.

(3. The method ot recovering salts from brine containinga mixture oii'sodium and potassium salts which comprises adding to the brine ammonia and an aquemis solution oi a sulfate.

In testimony whereof I have signed my name to this specification.

onmron nonnniini 

